Energy transfer between radiant energy and electrical energy can be performed in either of two directions. In one direction, such as when using a solar photovoltaic cell, absorbed radiant energy is converted to an electrical charge that can be directly used or stored. In the other direction, such as when using a lamp, lighting element, or self luminescent display, electrical current is used to provide radiant energy.
In conventional practice, standard point-to-point wiring connections have been used in order to provide the electrical connection to an energy-producing or light-producing element. With the recent maturing of a number of radiant energy transfer technologies, however, there may be opportunities for improving upon conventional techniques. Of particular interest are methods for electrical interconnection with a new generation of thin, large-area panels that are well suited to either absorb light or to provide light.
In the energy generation arena, numerous companies are developing inexpensive roll coated substrates with materials that generate electricity from sunlight. For example Nanosolar Inc., Palo Alto, Calif. has developed a technology for providing flexible solar panels that are lightweight and robust. Thin photovoltaic panels of this type maximize the area for light absorption and may promise a good degree of conformance to surfaces that are non-planar. Due to their lightweight construction and low profile, flexible photovoltaic panels such as those proposed by Nanosolar Inc. are easier to mount in place, not requiring supporting structural enhancements to buildings, such as those often needed with earlier solar power technologies.
For radiant energy transfer in the opposite direction, thin-panel electroluminescent solid state lighting offers the promise of reduced energy consumption and increased efficiency for a range of lighting and display applications. One of the key contending technologies for the solid-state lighting market is the organic light emitting device (OLED). Originally developed for small-scale display applications, OLEDs have also been proposed as replacements for conventional light sources. As just one example of OLED use for illumination, commonly-assigned U.S. Pat. No. 6,819,036 (Cok) discloses a solid state lighting device with a removable OLED that is outfitted for an electrical socket.
As they increase in size and light output efficiency, OLEDs have attracted considerable attention for larger scale illumination uses. A report entitled “Organic Light Emitting Diodes (OLEDs) for General Illumination Update 2002” from the Optoelectronics Industry Development Association, Washington, D.C. suggests strongly that OLED panels and related devices will be formidable contenders for the lighting market. In comparison with existing lighting technologies, it is anticipated that OLED illumination panels would provide high levels of energy efficiency and pleasing white light with high CRI (color rendition index).
Large-scale OLED panels could provide a viable alternative to fluorescent and incandescent lighting. In addition, OLED illumination panels offer new capabilities for illumination applications. Because the OLED device itself is made up of extremely thin layers of material, an OLED illumination panel can be made to be comparatively lightweight and would be well suited for use where a compact light source is desirable. U.S. Patent Application Publication No. 2004/0252488 (Thurk) gives examples of one type of embodiment, using a large-scale OLED assembly for room illumination.
Another attractive aspect of the OLED device relates to flexible substrates. Because the OLED device can be formed on any number of different substrates, including a fabric or plastic backing material, an OLED illumination panel could be made to adapt to a surface shape, bending around corners or conformal to curved surfaces, for example.
Significant research and development have been directed to improving the energy efficiency, manufacturability, and cost of OLED technology, needed in order to make larger scale OLED illumination panels a reality. For example, U.S. Patent Application Publication No. 2005/0094394 (Padiyath et al.) describes a method of web fabrication for thin OLED segments that allows connection of an array of larger scale OLED components in series or in parallel.
In addition to OLED electroluminescent technology, other thin-panel technologies that offer the promise of high efficiency illumination are being developed. One proposed alternate approach is to use quantum dots in combination with either an electric field or another illumination source to provide white light. Quantum dots are made up of groupings of a very small number of atoms of material with typically less than 100 available free electrons. Upon driving this material electrically or photonically, quantum dots can emit efficient white light. When combined in a polymer, quantum dots can be coated onto a flexible substrate to provide a wide area illuminator. Other methods for providing electroluminescence include using nanoparticles.
While attention has been focused on thin-panel radiant energy transfer device development and fabrication, however, making such devices practical and benefiting from their inherent advantages will also require appropriate techniques for panel mounting and connection. While conventional wiring and mounting techniques could be employed, these methods may constrain the usability of OLED and other radiant energy transfer panels and could fail to take advantage of features such as light weight, surface conformability, and ease of handling for reconfiguration. In addition, other anticipated features of large-scale radiant energy transfer panels, such as the likely capability to reduce panel size, at least with respect to one dimension, present new challenges for providing mounting and electrical connection to these devices.
Thus, there is a need for connection methods and apparatus that take advantage of radiant energy transfer panel characteristics such as conformability, variable dimensioning, and light weight, and that would allow facile mounting, relocation, removal, and replacement of radiant energy transfer panels for generating or obtaining electrical energy from light.